Highly Selective Hydrogenation of CO2 to Ethanol via Designed Bifunctional Ir1–In2O3 Single-Atom Catalyst

Recently, CO 2 hydrogenation for the controlled growth of the carbon chain to produce high-value C 2 or C 2+ products has attracted great interest, where achieving high selectivity for a specific product remains a challenge, especially for ethanol. Herein, we have designed a bifunctional Ir 1 –In 2 O 3 single-atom catalyst, integrating two active catalytic centers by anchoring the monatomic Ir onto the In 2 O 3 carrier. This Ir 1 –In 2 O 3 single-atom catalyst is efficient for the hydrogenation of CO 2 in liquid, yielding a high selectivity for ethanol (>99%) with an excellent initial turnover frequency (481 h –1 ). Characterization shows that the isolated Ir atom couples with the adjacent oxygen vacancy forming a Lewis acid–base pair, which activates the CO 2 and forms the intermediate species of carbonyl (CO*) adsorbed on the Ir atom. Coupling this CO* with the methoxide adsorbed on the In 2 O 3 forms a C–C bond. The strategy of this effective bifunctional single-atom catalyst by synergistically utilizing the distinct catalytic roles of the single-atom site and the substrates provides a new avenue in catalyst design for complex catalysis.